American Psychiatric Association: Diagnostic and Statistical Manual of Mental Disorders, 4th edn. text rev. American Psychiatric Association, Washington, DC, 2000
Baird G, Charman T, Baron-Cohen S, et al: A screening instrument for autism at 18 months of age: A 6-year follow-up study. J Am Acad Child Adolesc Psychiatry 39: 694-702, 2000
Baranek GT: Autism during infancy: A retrospective video analysis of sensory-motor and social behaviors at 9-12 months of age. J Autism Dev Disord 29: 213-234, 1999
Baron-Cohen S, Allen J, Gillberg C: Can autism be detected at 18 months? The needle, the haystack, and the CHAT. Br J Psychiatry 161: 839-843, 1992